Classification Definition
This invention relates generally to automatic transmissions for automobiles, trucks, buses and other appliances, and more particularly to an automatic transmission combined with an internal combustion engine for vehicles.
1. An automatic transmission usually comprises: a fluid torque converter connected to an internal combustion engine for transmitting torque from the engine to the driving wheels. The torque generated by the engine is transmitted in various gear ratios to the driving wheels in cooperation with said fluid converter and a gear mechanism. However an automobile provided with a hydraulic transmission is said to be less powerful, especially at "standing time" if compared with a vehicle provided with a manual transmission. This is explained because the efficiency range of the engine is restricted when using a fluid torque converter.
FIG. 3 shows the engine torque curve and a fluid torque converter efficiency range on a coordinate system where: Ne (engine rpm) is a function of Te (engine torque) wherein lines X and Y indicates the fluid torque converter efficiency range and line Z indicates the available maximum engine torque curve, according with its capacity. Avoiding the use of the fluid torque converter said engine torque is available in a uniform way below curve Z. However when using it in combination with a fluid torque converter the available range is limited to within the area enclosed by the lines X, Y and curve Z. The point "A" represents the "stall point" and it means that this is the maximum engine rpm in which the fluid torque converter output is still motionless. From this condition the time of "standing start" to a quarter mile is measured. The fact that an automobile having a hydraulic transmission has a longer "standing start" time that one having a manual transmission is based on the following reasoning: in FIG. 3 at "stall point" "A" the horse power is only 40 HP, although the engine is designed to provide more than 100 HP. It may be possible for a driver to manually bring the "stall point" up to the point "C" where the horse power is 65 HP if the vehicle is provided with a manual transmission. It is also possible to use a more efficient fluid torque converter so as to rise the "stall point". However in this case fuel efficiency will be decreased due to non-matching of the engine and the fluid torque converter capacities.
According to the present invention, a mechanic torque converter is provided interconnecting: an engine output; the driving wheels input; and a fluid torque converter, combined in such a way that at "starting time" when applying a brake band on the second planetary system ring gear of said mechanic torque converter, a torque is transmitted 100% in a mechanic way to the driving wheels, for an excellent mechanic efficiency and at this point the highest gear ratio is attainable due to the fact that a significant resistance is found at the driving wheels and a reaction takes place at the fluid torque converter which is transmitted to the mechanic torque converter for producing a change in the mechanic gear ratio. When vehicle starts moving the resistance becomes less at the driving wheels then, less resistance is found at the turbine at the fluid torque converter and a change in gear ratio takes place in both converters then, a smaller gear ratio is attainable according with the vehicle driving conditions. It is also possible to vary the efficiency range of the fluid torque converter itself because of the interaction of the mechanic torque converter thus, it may be possible to have the performance of the mechanic transmission, especially noticeable at "starting time" or when a significant resistance is found at the driving wheels, combined with a hydraulic transmission performance of equivalent gear ratio applied at the same time to a common converters output, without steps where no sensors, multi-disc clutches, "hydraulic brains" or complex hydraulic circuits are involved, for less components and a lower production cost.
1. An automatic transmission usually has a gear mechanism comprising two planetary gear systems. PA1 2. An automatic transmission usually is never connected with the vehicle brake system.
According to the present invention both planetary gear systems used herein are exactly of the same geometrical dimensions then, taken into account that when a greater amount of parts of the same manufacture are made, the less the production cost and, if devices; machines as well as operative workers intervening in the process are the same one, the more the simplified production process.
According to the present invention, the vehicle brake system is connected with the first brake band servo in order to stop turbine T rotation for shifting purposes, but as brake drum FIGS. 1, 2, and 4 is also interconnected with the driving wheels then, when vehicle's brake is applied, said brake drum and driving wheels are braked at the same time.